Cardiopulmonary effects of continuous pressure breathing in hypothermic dogs

1965 ◽  
Vol 20 (4) ◽  
pp. 669-674 ◽  
Author(s):  
J. Salzano ◽  
F. G. Hall
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Alveolar Ventilation ◽  
Positive Pressure ◽  
Negative Pressure Breathing ◽  
Continuous Positive Pressure ◽  
Respiratory Dead Space

Continuous pressure breathing was studied in hypothermic anesthetized dogs. Alveolar ventilation decreased during continuous positive-pressure breathing and increased during continuous negative-pressure breathing. The changes in alveolar ventilation were due to changes in respiratory rate as well as in respiratory dead space. Cardiac output fell significantly during continuous positive-pressure breathing due to a reduction in heart rate and stroke volume. During continuous negative-pressure breathing cardiac output was only slightly greater than during control as a result of a fall in heart rate and an increase in stroke volume. Oxygen consumption was reduced to 60% of control during continuous positive-pressure breathing of 16 cm H2O but was 25% greater than control during continuous negative-pressure breathing. Qualitatively, CO2 production changed as did O2 consumption but was different quantitatively during continuous negative-pressure breathing indicating hyperventilation due to increased respiratory rate. Mean pulmonary artery pressures and pulmonary resistance varied directly with the applied intratracheal pressure. The results indicate that the hypothermic animal can tolerate an imposed stress such as continuous pressure breathing and can increase its oxygen consumption during continuous negative-pressure breathing as does the normothermic animal. hypothermia; respiratory dead space; metabolic rate; cardiac output Submitted on December 8, 1964

Cardiovascular changes in the exercising emu

1983 ◽  
Vol 104 (1) ◽  
pp. 193-201 ◽  
Author(s):  
B. Grubb ◽  
D. D. Jorgensen ◽  
M. Conner
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Oxygen Content ◽  
Body Mass ◽  
Fold Increase ◽  
Exercise Heart Rate ◽  
Rate Of Oxygen Consumption ◽  
Cardiovascular Variables

Cardiovascular variables were studied as a function of oxygen consumption in the emu, a large, flightless ratite bird well suited to treadmill exercise. At the highest level of exercise, the birds' rate of oxygen consumption (VO2) was approximately 11.4 times the resting level (4.2 ml kg-1 min-1). Cardiac output was linearly related to VO2, increasing 9.5 ml for each 1 ml increase in oxygen consumption. The increase in cardiac output is similar to that in other birds, but appears to be larger than in mammals. The venous oxygen content dropped during exercise, thus increasing the arteriovenous oxygen content difference. At the highest levels of exercise, heart rate showed a 3.9-fold increase over the resting rate (45.8 beats min-1). The mean resting specific stroke volume was 1.5 ml per kg body mass, which is larger than shown by most mammals. However, birds have larger hearts relative to body mass than do mammals, and stroke volume expressed per gram of heart (0.18 ml g-1) is similar to that for mammals. Stroke volume showed a 1.8-fold increase as a result of exercise in the emus, but a change in heart rate plays a greater role in increasing cardiac output during exercise.

Cardiac Manifestations of Systemic Diseases and Pregnancy

2016 ◽  
pp. 45-52
Author(s):  
Lori A. Blauwet ◽  
Rekha Mankad ◽  
Sabrina D. Phillips ◽  
Kyle W. Klarich
Keyword(s):  
Heart Rate ◽  
Weight Loss ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Myocardial Oxygen Consumption ◽  
The Elderly ◽  
Systemic Diseases ◽  
Exertional Dyspnea ◽  
Cardiac Manifestations

Cardiovascular manifestations of hyperthyroidism include increased heart rate, stroke volume, and cardiac output. Peripheral vascular resistance is decreased, and thus pulse pressure is widened. As a result, myocardial oxygen consumption increases, which may precipitate angina. Other symptoms include palpitations, presyncope or syncope, and exertional dyspnea. Arrhythmias may occur. Common symptoms include weight loss, weakness (especially in the elderly), and tachycardia or palpitations.

scholarly journals Respiratory pump maintains cardiac stroke volume during hypovolemia in young, healthy volunteers

2018 ◽  
Vol 124 (5) ◽  
pp. 1319-1325 ◽  
Author(s):  
Maria Skytioti ◽  
Signe Søvik ◽  
Maja Elstad
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Healthy Volunteers ◽  
Negative Pressure ◽  
Spontaneous Breathing ◽  
Positive Pressure Ventilation ◽  
Control Mode ◽  
Positive Pressure ◽  
Beneficial Effects ◽  
Cardiac Stroke Volume

Spontaneous breathing has beneficial effects on the circulation, since negative intrathoracic pressure enhances venous return and increases cardiac stroke volume. We quantified the contribution of the respiratory pump to preserve stroke volume during hypovolemia in awake, young, healthy subjects. Noninvasive stroke volume, cardiac output, heart rate, and mean arterial pressure (Finometer) were recorded in 31 volunteers (19 women), 19–30 yr old, during normovolemia and hypovolemia (approximating 450- to 500-ml reduction in central blood volume) induced by lower-body negative pressure. Control-mode noninvasive positive-pressure ventilation was employed to reduce the effect of the respiratory pump. The ventilator settings were matched to each subject’s spontaneous respiratory pattern. Stroke volume estimates during positive-pressure ventilation and spontaneous breathing were compared with Wilcoxon matched-pairs signed-rank test. Values are overall medians. During normovolemia, positive-pressure ventilation did not affect stroke volume or cardiac output. Hypovolemia resulted in an 18% decrease in stroke volume and a 9% decrease in cardiac output ( P < 0.001). Employing positive-pressure ventilation during hypovolemia decreased stroke volume further by 8% ( P < 0.001). Overall, hypovolemia and positive-pressure ventilation resulted in a reduction of 26% in stroke volume ( P < 0.001) and 13% in cardiac output ( P < 0.001) compared with baseline. Compared with the situation with control-mode positive-pressure ventilation, spontaneous breathing attenuated the reduction in stroke volume induced by moderate hypovolemia by 30% (i.e., −26 vs. −18%). In the patient who is critically ill with hypovolemia or uncontrolled hemorrhage, spontaneous breathing may contribute to hemodynamic stability, whereas controlled positive-pressure ventilation may result in circulatory decompensation. NEW & NOTEWORTHY Maintaining spontaneous respiration has beneficial effects on hemodynamic compensation, which is clinically relevant for patients in intensive care. We have quantified the contribution of the respiratory pump to cardiac stroke volume and cardiac output in healthy volunteers during normovolemia and central hypovolemia. The positive hemodynamic effect of the respiratory pump was abolished by noninvasive, low-level positive-pressure ventilation. Compared with control-mode positive-pressure ventilation, spontaneous negative-pressure ventilation attenuated the fall in stroke volume by 30%.

Initial hemodynamic responses to mild exercise in trained dogs

1965 ◽  
Vol 20 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Harold Smulyan ◽  
Richard P. Cuddy ◽  
William A. Vincent ◽  
Udomporn Kashemsant ◽  
Robert H. Eich
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Right Atrium ◽  
Initial Reaction ◽  
Hemodynamic Responses ◽  
Heart Rates ◽  
Infusion Method ◽  
The Right

The transient changes in cardiac output at the onset of mild exercise were measured in dogs trained to walk on a treadmill. Cardiac output was obtained using a krypton 85 infusion method, which permitted frequent determinations of flow. The first go sec of exercise were marked by a prompt rise and overshoot of heart rate and cardiac output, whereas increases in stroke volume occurred later after the onset of exercise, and to a lesser extent than heart rate. At rest, the right atrium was electrically driven at rates slightly faster than heart rates attained spontaneously with exercise and the studies repeated. Changes in cardiac output with exercise were similar to those in unpaced animals, but when the heart rate was fixed stroke volume increased immediately. These studies show a consistent rise in heart rate and cardiac output in the initial reaction to exercise, but when the prompt rise in heart rate was prevented by pacing from the right atrium, increases in stroke volume provided a comparable response in cardiac output. krypton 85; cardiac output; stroke volume; pacing of heart; oxygen consumption Submitted on September 23, 1964

CARDIOVASCULAR EFFECTS OF PRONETHALOL IN THE DOG

1965 ◽  
Vol 43 (3) ◽  
pp. 411-420 ◽  
Author(s):  
M. A. Chiong ◽  
P. F. Binnion ◽  
J. D. Hatcher
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Peripheral Resistance ◽  
Systolic Pressure ◽  
Cardiovascular Effects ◽  
Stroke Work ◽  
Right Ventricular Systolic Pressure ◽  
Ventricular Systolic Pressure

The cardiovascular effects of an intravenous injection of pronethalol (2.5 mg/kg) and the effect of this agent on the cardiovascular changes induced by an infusion of adrenaline (0.2 μg/kg per minute) were investigated in intact anaesthetized dogs. Fifteen minutes after the administration of pronethalol, significant increases were observed in oxygen consumption, right ventricular systolic pressure, and haematocrit, and decreases in arterial blood pressure and total peripheral resistance. Arterial hypotension and a fall in stroke work were the only changes noted at 30 minutes. There was considerable variability in cardiac output, stroke volume, and heart rate but, on the average, no significant change was observed. Pretreatment with pronethalol abolished or significantly reduced the adrenaline-induced rises in cardiac output, heart rate, stroke volume, stroke work, oxygen consumption, right ventricular systolic pressure, and arterial haematocrit, and reversed the changes in diastolic arterial pressure and peripheral resistance. It is concluded that pronethalol is not devoid of sympathomimetic activity and that it effectively blocks the adrenaline responses mediated by β-receptors.

Response to exercise in dogs with cardiac denervation

1963 ◽  
Vol 205 (2) ◽  
pp. 393-400 ◽  
Author(s):  
David E. Donald ◽  
John T. Shepherd
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Equivalent Dose ◽  
Cardiac Denervation ◽  
Modest Increase ◽  
Severe Exercise ◽  
Response To Exercise

Dogs with chronic cardiac denervation by the technic of regional neural ablation showed an unchanged capacity for work as measured by oxygen consumption. The relation of cardiac output to oxygen consumption during exercise remained unchanged from preoperational values. When the dogs started to run, the heart rate rose slowly over 1.5 min to reach a steady value proportional to the work performed. When exercise was stopped, the heart rate declined slowly. With mild exercise, the increase in cardiac output was mainly through stroke volume; with more severe exercise, increase in stroke volume and heart rate contributed equally, in contrast to the normal dog where the increase in rate predominates. Neither the pattern of the change in heart rate nor the plateau values were altered by adrenalectomy. The change in rate was not attributable to change in intravascular temperature. In an equivalent dose of base, norepinephrine caused tachycardia but little or no change in cardiac output, whereas epinephrine resulted in an increase in cardiac output with but a modest increase in heart rate.

Cardiovascular responses of man during negative-pressure breathing

1960 ◽  
Vol 15 (4) ◽  
pp. 557-560 ◽  
Author(s):  
E. Y. Ting ◽  
S. K. Hong ◽  
H. Rahn
Keyword(s):  
Heart Rate ◽  
Negative Pressure ◽  
Venous Pressure ◽  
Cardiovascular Responses ◽  
Positive Pressure ◽  
Reduced Pressure ◽  
Cavity Collapse ◽  
Blood Pressures ◽  
Negative Pressure Breathing ◽  
Finger Plethysmography

Blood pressures, heart rate and finger volumes were recorded while supine subjects submitted to various degrees of continuous negative-pressure breathing. The lowest pressure was –30 cm H2O. Systolic and diastolic arterial pressures as well as heart rate remained essentially unchanged. The peripheral venous pressure estimated by an indirect method was slightly lowered. Finger plethysmography indicated a peripheral vasoconstriction to the same degree as observed during positive-pressure breathing. Various considerations suggest that during negative-pressure breathing the veins entering the thoracic cavity collapse and effectively divide the circulation into the thoracic one which operates at a considerably reduced pressure, and the nonthoracic circulation which is maintained at normal pressures. The pressure difference between these two circulations is maintained by the left ventricle. Submitted on February 8, 1960

Cardiovascular response to graded exercise in the sympathectomized-vagotomized dog

1963 ◽  
Vol 204 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Edmundo Ashkar ◽  
William F. Hamilton
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Mean Arterial Pressure ◽  
Stroke Volume ◽  
Cardiovascular Response ◽  
Peripheral Resistance ◽  
Graded Exercise ◽  
Oxygen Difference

Seven dogs who ran well on a motor-driven treadmill were completely sympathectomized (including adrenal denervation) and subjected to unilateral vagotomy below the recurrent laryngeal branch. After recovery and retraining, a terminal experiment was performed in which, after completing the vagotomy, direct Fick determinations of cardiac output and continuous recordings of mean arterial pressure, heart rate, and oxygen consumption were made at rest and during increasing exercise The results were compared with those described by Barger et al. ( Am. J. Physiol. 184: 613, 1956) for normal dogs running at smaller speeds and grades. The heart rate of the operated dogs increased from 117 to 134. Barger's normal dogs doubled their heart rate. The A-V oxygen difference increased with work slightly less than Barger's normal dogs but the scatter in both groups was wide, as was the case with the stroke volume. The resting cardiac output was nearly normal in the operated dogs but increased only 34% with exercise, as against 200–300% in Barger's normals. Oxygen consumption increased about twofold as against the expected normal of three- to sevenfold. Peripheral resistance in both groups went down about 40%. The blood pressure in the normal increased substantially while that in the operated dogs fell about 20% to an average of 60 mm Hg.

Cooling Responses in Shivering and Non-Shivering Dogs during Induced Hypothermia

1980 ◽  
Vol 58 (6) ◽  
pp. 501-506 ◽  
Author(s):  
C. D. Auld ◽  
I. M. Light ◽  
J. N. Norman
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Oxygen Extraction ◽  
Induced Hypothermia ◽  
Oxygen Utilization ◽  
Sustained Increase

1. Hypothermia to a temperature of 30°C was induced in both shivering and non-shivering groups of dogs. 2. There was a sustained increase in oxygen consumption in the dogs allowed to shiver and this was up to 300% greater than the oxygen consumption in the relaxed dogs. 3. The increased tissue requirement for oxygen was met both by increased cardiac output and increased oxygen extraction from haemoglobin. 4. Oxygen utilization remained adequate in hypothermia, as shown by the absence of hypoxic acidosis. 5. Heart rate fell during cooling and stroke volume increased to meet the increased oxygen demands associated with shivering during the induction of hypothermia.

Submaximal Cardiovascular Responses to Exercise in Children: Treadmill versus Cycle Ergometer

1997 ◽  
Vol 9 (4) ◽  
pp. 331-341
Author(s):  
Kenneth R. Turley ◽  
Jack H. Wilmore
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Regression Analysis ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Peripheral Resistance ◽  
Cardiovascular Responses ◽  
Cycle Ergometer ◽  
Individual Values ◽  
Oxygen Difference

This study investigated whether cardiovascular responses at a given submaximal oxygen consumption (V̇O2, L · min-1) are different between the treadmill (TM) and cycle ergometer (CE). Submaximal cardiovascular measurements were obtained at three work rates on both the TM and CE in 7- to 9-year-old children (12 males and 12 females). Using regression analysis, it was determined that there were no differences between the TM and CE in cardiac output (L · min-1), stroke volume (SV, ml · beat-1) or heart rate (beats · min-1) at a given V̇O2 (L · min-1). There were differences in the total peripheral resistance (TPR, units) and arterial-venous oxygen difference (a-vO2 diff, ml · 100 ml-1) to V̇O2 (L · min-1) relationship. While there were statistically significant differences in TPR and a-vO2 diff between the two modalities, there was substantial overlap of individual values at any given submaximal V̇O2, thus the physiological significance is questionable. Hence, we conclude that in 7- to 9-yearold children there are no differences in submaximal cardiovascular responses between the CE and TM.

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